A mounting mechanism for mounting a taping head in an upper bridge structure of a tape applying machine includes J-configured slots that are engaged by pin members extending from the taping head. A tape supply roll holder for holding a supply roll of tape for a lower taping head disposed on a carriage of the tape applying machine. The tape supply roll holder holds the roll of tape at a position that is viewable by the operator of the machine. A mechanical stop retains a pneumatically operable bridge structure in a raised position in the tape applying machine when the pneumatic circuit is in non-operable state. An emergency stop switch means is disposed on an upper surface of the bridge structure such that it is accessible from either side of the machine. A pair of spaced apart compression rollers are positioned to engage upper opposing portions of a box traveling across the carriage so that edge portions of upper flap members of the box are positioned in substantially parallel relationship to each other for taping by the upper taping head.